Help Please

Hi I had my for sure last period between March 20-23,2013. I have irregular periods. I practically gushed out blood on April 11th during an argument with my ex. By the next day I was not bleeding anymore. Me and my ex boyfriend(Guy 1) had sex the last time around March 29,2013. We did not use a condom but I think he pulled out. We lived together having unprotected sex for 2 years on and off of bc and has never gotten pregnant. I had gotten off BC in February. I also had sex with someone around April 25, 2013(Guy 2) and we did not begin with a condom but i told him to put one on I cant remember if he took it back off but I know he didn't nut in me , I feel like he took it off. Guy 3 around April 28 and May 5. We did not use a condom the second time, he pulled out. I was very watery thin and a very small amount. My uterus is measuring exactly 24 weeks but my current US measurements are estimating at 22  I am 23 weeks and 5 days according to a LMP of April 5th on an ultrasound. I didn't bleed or anything on April 5th. My first US is what puts me at 23w5d, the more recent ones are putting me at around 22w6d.  WAS APRIL 11TH A PERIOD? WHO IS THE FATHER?